Update to GCC 10, clang 12

[isuruf]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[beckermr]

We've been using major compiler versions to demark psuedo-epochs in the compiler stack in order to help ease the transitions to new features/packages. For example, we did this with the sysroot work.

Before we do this, is there anything we want to bump and/or change?

[isuruf]

I can't think of anything to change.

[h-vetinari]

Based on how I read the compatibility matrix for CUDA, this could (should?) also bump to GCC 10 for CUDA 11.1+

[h-vetinari]

I have an open comment how we can/should deal with this in staged recipes (the answer may be "do nothing", though then we'd either have to stay on GCC 9 or drop CUDA <=11.0 in staged recipes, unless I'm overlooking something somewhere...).

[h-vetinari]

Comment resolved, looking forward to this!